Apparatus for tensioning reinforcing strands for belts and the like



March 24; 1970 H. J. BONGERS ETA!- 3,502,535

APPARATUS FOR TENSIQNING RBINPORCING STRANDS FOR BELTS mm mm mm FiledApril 28, 1967 4 Shaets -Sheet 1 Ila F' I6. I

A TTORNE).

March 24, 1970 H.J. BONGERS ETAL 3,502,535

APPARATUS FOR TENSIONING REINFORCING STRANDS FOR BELTS AND THE LIKEFiled April 28, 1967 4 Sheets-Sheet 2 FIG.2

H J 81 ZVENTORS NGERS W/NFRIED WITZFELD A rraawsy' March 24, 1970 H. J.BONGERS E AL Y 3,502,535

APPARATUS FOR TENSIONING REINFORCING STRANDS FOR BELTS AND THE LIKEFiled April 28, 1967 4 Sheets-Sheet 3 [2 I I I I I INVENTORS H J.BONGERS WINFRIEO MOITZFELD Y FIG. 3 fKar A TTORNEY March 24, 1970 FiledApril 28. 1967 H. J. BONGERS ET AL APPARATUS FOR TENSIONING REINFORCINGSTRANDS FOR BELTS AND THE LIKE 4 Sheets-Sheet 4 FIGS 1N VENTORS H. J.BONGEQ BY W/NFRIED MOITZiELO United States Patent 3,502,535 APPARATUSFOR TENSIONING REINFORCING STRANDS FOR BELTS AND THE LIKE HendrikusJohannes Bongers and Winfried Moitzfeld, Krefeld, Germany, assiguors toG. Siempelkamp 82 C0., Krefeld, Germany, a corporation of Germany FiledApr. 28, 1967, Ser. No. 634,749 Claims priority, application Germany,Apr. 30, 1966,

S 103,571 Int. Cl. 33% /04, 32/10; B65h 77/00 US. Cl. 156-494 10 ClaimsABSTRACT OF THE DISCLOSURE Apparatus for the production of reinforcedelongated flexible belts wherein an array of mutually parallellongitudinally extending tensioned reinforced strands are bondedrespective layers, wherein the wire-tensioning device includes a support(eg a cylinder block) extending transversely of array and provided witha plurality of individually movable tensioning members in the form ofindividual pistons respectively aligned and engageable with the strands;a hydraulic arrangement for shifting the support relative to said arrayin vertical direction for preliminary tensioning of the strand; andhydraulic cylinders for shifting the members individually for finaltensioning of the respective strands.

The present invention relates to apparatus for the production ofconveyor belts, bands and other relatively elongated bodies ofelastomeric material having longitudinally extending reinforcing strandsand, more particularly, to a strand-tensioning device for suchinstallations.

In the commonly assigned copending application Ser. No. 611,620, filedJan. 25, 1967, now Patent No. 3,459,848, and entitled Method of andApparatus for the Manufacture of Reinforced Flexible Belts; there isdisclosed and claimed an apparatus for the production of rubber conveyorbelts and the like in which, downstream of a vulcanizing press, aplurality of stations are located for applying a pair of elastomericstrips to a planar array of steel reinforcing wires or strandsindividually stressed by suitable tensioning means. In this system, thestrands may pass through a wire-straightening means to form a generallyflat array of mutually parallel, transversely spaced, steel reinforcingwire; a pair of supply devices for applying respective core strips tothe array of reinforcing wires; means for applying outer rubber strips;an equalizing precompression press for intermittently compacting theelastomeric bands about the wires; and means for vulcanizing theflexible layers of the core and the outer layers to the reinforcingstrands. The system operates substantially continuously, i.e. the bandpasses in steps through the vulcanizing press, while the core layers andouter strips are applied more or less continuously via a travelingcarriage. It has been found to be important in such installations tomaintain the steel reinforcing Wires under tension during the pressstroke and during the application of the several rubber layers to thearray of core Wires and, moreover, to maintain each of the strands at anindividual tension substantially independently of the remaining strands.In this manner, slackening of one or more strands at any of the stagesin which the reinforcing array, core or band are clamped, is precludedand the pretension of the strands can be determined by the needs of thefinished belt. Heretofore, such tensioning was effected by passing thecable or Wire about a plurality of pulleys at least'one of which wasWeighted by direct application of a calibrated spring, by theapplication of a selected number of calibrated weights or bypredetermined stressing of a lever upon which the tensioning pulley was3,502,535 Patented Mar. 24, 1970 mounted. Such systems have not,however, been highly successful and have often required clamping meansboth on the inlet and outlet side of the tensioning device, which causedproblems with respect to the continuity of conveyor-belt production.Moreover, the systems were impractically large, of expensive and complexmanufacture and required continuous time-consuming adjustment.

It is, therefore, the principal object of this invention to provide animproved tensioning device in an apparatus for the manufacture ofconveyor belts and the like, whereby the individual reinforcing elementscan be tensioned selectively and relatively high levels of tension canbe applied to the entire array.

It may be noted that there have been proposed systems in which themovable pulley of a tensioning device has been hydraulically actuated,but these systems too have experienced difliculties especially withrespect to the dimensioning of the unit. For example, when relativelyhigh levels of tension must be attained, the economics of the hydraulicsystem requires that the cylinders have relatively large diameters. Onthe other hand, the individual Wires or reinforcing elements must berelatively closely spaced in conveyor-belt assemblies and the mutualcontradiction of these two requirements have proved incapable ofoptimization in conventional systems. Furthermore, the strokes of theindividual pistons for the desired level of tensioning varies with theyieldability or elongatability of the tensioned elements and even theinitial tensioning movements frequently have exceeded the capacity ofconventional units of this type.

It is therefore a specific object of this invention to provide animproved hydraulic apparatus for the individual tensioning of the coreelements of a conveyor belt whereby the disadvantages of earlierhydraulic systems can be obviated.

Still another object of this invention is to provide a relatively simpleand economical device for selectively and individually tensioning amultiplicity of relatively closely spaced reinforcing strands of aconveyor belt-production plant and for collectively prestressing same.

These objects and others, which will become apparent hereinafter, areattained, in accordance with the present invention, by an installationfor the production of conveyor belts and like relatively elongated flatbodies having an array of mutually parallel transversely spacedreinforcing strands as described and claimed in application Ser. No.611,626 of January 25, 1967, wherein, how ever, the means forindividually tensioning the reinforcing wires comprises a cylinderassembly having a plurailty of hydraulic cylinders each associated witha respective reinforcing strand and having a respective pistonengageable with this strand via a tensioning pulley or the like, thecylinder assembly being provided with means for shifting it in thedirection of movement of the individual tensile pistons. "l histensioning system is used, of course, in conjunction with an inputclamping means between the wire-supply apparatus and the tensioningsystem, and an output clamping means between the tensioning system andthe layer-applying arrangement. the cylinder assembly, according to thisinvention, comprises a cylinder block running athwart a multiplicity ofthe transversely spaced mutually parallel reinforcing strands and isprovided with a multiplicity of cylinder bores extending perpendicularlyto the plane of the array of strands, each bore having an axial plane inwhich the corresponding strand substantially lies. The bores aredisposed in staggered relationship on opposite sides of a median planeperpendicular to the array and, advantageously forming an axial plane ofthe mechanism for raising and lowering the cylinder block. Thismechanism can comprise a further hydraulic cylinder whose piston issurmounted by the block and vertically shifts the latter with respect toa framework above the array in which the idler pulleys are journaled.Thus, the tensioning elements associated with each strand can comprise apair of idler pulleys dependent from the frame and longitudinally spacedin the direction of movement of these strands and a vertically shiftablepulley disposed between the depending idler pulleys and carried by therespective piston which slidably is received in the cylinder boredirectly below the strand. The pretensioning or main cylinder will, ofcourse, be dimensioned to carry the cylinder block and to apply apreliminary stress to all of the strands associated therewith via theindividual tensioning pistons. Advantageously, the cylinder bores of thecommon block are connected in parallel to a common hydraulic linethrough which hydraulic fluid is supplied to the tensioning pistons.

In operation, the steel wires are individually threaded through astraightening device, if necessary, from the supply wheels and then arepassed through the input clamp, around the idler-tensioning pulleys ofthe individual tensioning assembly, drawn through the output clamp andthen passed through the layer-applying arrangement (see application Ser.No. 611,626) and introduced with the layers into the vulcanizing press.The array is then locked into position on the output side of thetensioning system via the output clamp and/or the vulcanizing press,while the input clamp is closed onto the array to apply a light pressureto the steel wires without, however, immobilizing them completely. Thusthe wires can be drawn through the input clamp during the tensioningaction against a frictional resistance of the platens.

During the initial tensioning movement, the cylinder block is raised andthe various elongatabilities of the reinforcing strands are compensatedby slip through the initial clamp which is then closed tightly. Thetensioning is now effected by further advance of the cylinder blockuntil the individual wires are pre-tensioned to a degree below thenormal level of tension for operation of the system. During thispre-tensioning period, there is at least a partial equalization of thetensile stress upon all of the wires. A further equalization of thetensile stress is effected by hydraulically charging the individualcylinders in parallel so that the pressure applied by the respectivepistons to each of the strands is identical throughout the array. When,however, the individual strands are to be tensioned to differentmagnitudes, the supply of hydraulic fluid to the individual cylindersafter the tensioning movement of the cylinder block will depend upon thehydraulic fluid pressure in the respective cylinder.

According to a further feature of this invention the manifold passagecommunicating with the cylinder bores of the block is providedintegrally (e.g. by machining) in the block, thereby eliminating theneed for flexible hydraulic lines and the like for each of theindividual tensioning arrangements. Advantageously, each of the cylinderbores is provided with a respective extension whose diameter is somewhatless than the diameter of the respective piston head and which iscoaxial therewith and machined into the cylinder block, these extensionscommunicating with lateral ducts opening into the manifold passage.

The pistons each are provided with blade-like extensions fixed to thepiston rods and carrying the tensioning pulleys which pass betweendepending blade-like members upon which the idlers are journaled. Theidler blades can be carried by a rack disposed directly above thecylinder block and having idler pulleys which are substantially tangentto the plane of the array.

The device thus occupies relatively little space and can be operatedwith a minimum of technological difficulty.

The above and other objects, features and advantages of the presentinvention will become more readily appar- 4 ent from the followingdescription, reference being made to the accompanying drawing in which:

FIG. 1 is an elevational view of a portion of an apparatus for makingconveyor belts and incorporating a tensioning device in accordance withthe present invention;

FIG. 2 is a plan view of the tensioning device, greatly enlarged andpartly diagrammatic, showing the lay-out of the idler pulleys, thetensioning pulleys and the cylinder bores;

FIG. 3 is a cross-sectional view taken along the line IIIIII of FIG. 2;

FIG. 4 is a cross-sectional view taken along the line IVIV of FIG 3; and

FIG. 5 is an elevational view of a modification of the tensioningdevice.

In FIG. 1, we show the tensioning system of an apparatus for theproduction of conveyor belts, the balance of which may be constituted asdescribed and illustrated in the copending application Ser. No. 611,626.The apparatus basically comprises a supply system S for delivering amultiplicity of strands 1, e.g. steel wires, from supply reels 20 to thevulcanizing press and the means for applying the rubber layers to thecore wires 1 and represented at A. The reels 20 are provided with axles21 rotatably received in notches 22 between a pair of support plates 23mounted upon a pedestal 24 of the supply station S. Each wire 1 passesaround a guide roll 25 so that, upon emergence from the supply device 3,the longitudinally extending, transversely spaced parallel wires 1 liein a horizontal plane represented at P. The Wires individually passthrough straightening eyes 26 of a straightening arrangement R which isconstituted as generally described in the aforementioned copendingapplication. Individual eyes 26 are mounted upon the pedestal 27 andform a comb-like guide for the parallel strands.

From the straightening device R the planar array of strands passesbetween the platens 2a, 2b of a clamping device 2 at the input side ofthe tensioning means represented at 4. The platen 2b rests upon thepedestal 2c of the clamp while the platen 2a is vertically movable(arrow 2d) and is guided by a frame 2e upon which a piston arrangement2] is disposed. The piston 21 of the latter carries the platen 2a and isdesigned to lower it into frictional engagement with the wires 1 orcomplete disengagement of the latter and into the tight gripping ofthese wires in the three positions of the clamp. The clamp isillustrated in greater detail in the aforementioned application.

The tensioning device 4 comprises, as can best be seen from FIGS. 1 and3, a traverse 7 which extends athwart the array of wires 1 above theplane P thereof and is provided with depending arms 7a and 7b instaggered pairs (see FIG. 2), each pair of arms 7a or 71) carrying arespective pair of stationary idler rollers 6. The rollers 6 of eachpair of arms and a respective roller 14 of the tensioning mechanism foreach wire is coplanar therewith, i.e. lies in a vertical plane P,, ofthe respective wire. The traverse 7 is fixed to a support structurerepresented diagrammatically at 70, and co-operates with the verticallyshiftable cylinder block 10 whose direction of movement is representedby the arrow 11. To this end the cylinder block 10 is supported on asystem 12a of a relatively large-diameter pre-tensioning hydrauliccylinder 12 in a well 11a of the plant. The cylinder block 10 isintegrally formed (FIG. 3) with a multiplicity of vertical bores 8 whichcan be provided with cylinder linings for sealing engagement with thehead 9 of the respective piston 9a. The cylinder bores 8 associated withthe adjacent strands 1 are staggered in two vertical planes P and Poffset in the direction of displacement of the wires 1 (arrow 11b). Thuseach of the pistons 9a and the respective bores 8 is disposed directlybeneath the respective strand 1 (FIG. 2), and the corresponding strandlies in the plane P,,, which, moreover, is an axial plane of thecylinder bore and the respective piston. The strand passing around eachpair of idlers 6 and the respective tensioning pulley 14 form atensioning loop 5 in the corresponding plane P two such loops beingillustrated in FIG. 3 in dot-dash and dotted lines, respectively. Thecylinder bores 8 are closed on the upper side of the cylinder block 10,which extends outward the array of wires 1 directly beneath and parallelto the traverse 7, by a blade a which is formed with openings 10bcoaxial with the bores 8 and slidably clearing the piston 911.

Each of the cylinder bores 8 is formed with a coaxial extension 8a of adiameter smaller than that of the piston head 9 and communicating with arespective bore a lying in the respective plane P and communicating witha manifold bore 15 running longitudinally through the block 10 betweenthe rows of cylinder bores 8. The cylinder bores 8 are thus fed withhydraulic fluid in parallel, the terminus 15b of the channel 15 beingsupplied with hydraulic fluid through a conventional control line. Thuseach of the pistons 911 can be shifted by the hydraulic fluid deliveredto the manifold channel 15 in the direction of arrows 9b while thecylinder block 10 is movable independently of this individual pistonmovement via the piston 12a and the cylinder 12 which, in turn, iscontrolled by a valve system not shown.

The pistons 9a each carries a blade-like extension 13, laterally offsetfrom the respective plane P (see FIG. 4), the blades 13 having .pins14:: upon which the respective pulleys 14 are journaled. Similarly, theblade-like depending arms 7a: of the traverse 7 carry pins 6a upon whichthe pulleys 6 are mounted. It will be understood that, while only asingle cylinder block 10 is illustrated in FIG. 2, the tensioning meanscan be subdivided transversely of the wires 1 and longitudinally of theblock into a plurality of cylinder blocks each having a respectivepiston 12 for its displacement. Each of these cylinder blocks will thenbe provided with a multiplicity of cylinder bores 8 with telescopingpistons 9, 9a. From FIG. 2, it can be seen that the branch channels 15aconnect the bores 8 in parallel to the manifold channel 15 so that thesame hydraulic pressure is maintained below the pistons 9, 9a, in eachbore 8 and, in spite of the fact that the strokes of these pistons mayvary with the degree of elongation of the reinforcing wires 1 and theneed to take up any slack therein, all of these Wires will beindividually tensioned to an identical prestress upon hydraulicenergization of the manifold channel 15.

Downstream of the wire-tensioning mechanism 4, there is provided themeans for applying the array of wires 1 a pair of core strips, aprecompression press for compacting the core strips about the array ofwires, a further device for applying the outer strips to the core thusformed and the vulcanizing press, all constituted as described in theaforementioned application Ser. No. 611,626 and located in the region Aof the plant.

Beyond the vulcanizing press, We provide a further clamping arrangement3 whose platens 3a and 3b engage the completed belt 3g when thevulcanizing press is opened. The platen 3b rests upon the pedestal 3c ofthis output clamp while a hydraulic cylinder arrangement 3] is carriedout by the frame 3e of the clamp and has pistons 3f which raise andlower the platen 3a.

In operation, the belt is fixedly held by the clamp 3 downstream of thetensioning device 4 through which the wires 1 from the supply reels havebeen threaded. The clamp 2 is closed to engage the wires 1 relativelylightly, i.e. to permit sliding movement of the wires 1 against africtional retarding force. The cylinder block 10 is then raised by thehydraulic-cylinder arrangement 12, 12a to form loops 5 (FIG. 3) in thewires 1 passing around each pair of fixed idler pulleys 6 and arespective tensioning pulley 14. The pre-tensioning force thus appliedto the wires compensates or equalizes the possibly non uniformlongitudinal yieldability of the steel reinforcing wires 1.

Thereafter, clamp 2 is tightened to fix the array of Wires upstream ofthe tensioning device 4 and hydraulic fluid is supplied to apply upwardhydraulic force of equal magnitude to all of the pistons 9, 9a andthereby subject the individual Wires 1 to a predetermined level ortension. The vulcanizing press can then be closed to bond the outerlayers to the core layers and the core layers to the reinforcing wires 1of the stretch of band within the vulcanizing press and which haspreviously passed through the layer-applying means. The pistons 9, 9aare, prior to the application of hydraulic fluid pressure to the block10 via the channel 15, in predetermined starting positions which may beintermediate positions with respect to their total stroke or endlimiting positions in which the pistons are fully received in therespective cylinder bores 8, depending upon the requirements of thesystem. Upon vulcanization of the stretch of band within the press,clamp 3 is opened, the press separated, clamp 2 is opened and the block10 lowered to release the wires 1 and permit a further length thereof tobe drawn to the line. As this length of wires is advanced, it is coatedwith the layers as described above and the sequence of steps fortensioning the wires is repeated.

It has been found that this system is highly advantageous not only forsteel reinforcing wires but for strands of material which are more orless extensive by comparison with steel. Thus, for example, the systemmay use monofilamentary or polyfilamentary synthetic resin strands,twisted or braided fiber cord or the like.

In FIG. 5, we show a modified tensioning device 40 which may besubstituted for the system illustrated in FIGS. 1-4 and which comprises,in place of the cylinder block 10, a beam 41 which carries amultiplicity of vertically shiftable and independently guided blademembers 42 carrying tensioning pulleys 43 adapted to co-operate with thepulleys 6 of the traverse 4 illustrated in FIG. 3. The guide means forthe bars 42 is represented by an elongated slot 44 in the beam 41 foreach of the bars and a guide pin 45 thereof, slidably received in therespective slot 44. The bars alternately disposed along the beam 41transversely of the wires 1 are staggered in the direction of the majordimension of the wires as illustrated at the left-hand sides of FIG. 2.To tension the wires 1 uniformly after the beam has been elevated byvertically shifting the bars 42, a flexible cable 46 is anchored to astationary support 47 via a relatively stiff coil spring 48 and tensionis applied to the flexible cable 46 via a cylinder 49 and its piston rod50. The cable 46 undershoots respective pulleys '51 journaled on thebars 42 below the tensioning pulleys 43 and overshoots stationary idlerroller '52 carried by uprights 53 upon the beam 41. The latter is, inturn, provided with a main hydraulic cylinder 54 Whose piston 54a raisesand lowers the beam.

The device in FIG. 5 operates generally in the manner previouslydescribed with the initial tensioning of the Wires 1 being effected by araising of the beam 41 by the hydraulic cylinder 54, 54a. Upon tightclosure of the clamp 2, tension is applied to the cable 46 by thehydraulic cylinder 49, 50 in the direction of arrow 55 and a uniformtension is applied via the loops 5 and the tension wheels 43 to theindividual wires with the wheels 43 and the bars 42 assuming relativevertical positions in dependency upon the degree of stretch of theindividual wires as may be necessary to reach the predetermined tension.

We claim:

1. In an apparatus for the production of reinforced elongated bodieswherein an array of mutually parallel longitudinally extending tensionedreinforcing strands are bonded to the body, the improvement whichcomprises a device for individually tensioning said strands, said deviceincluding a support extending transversely of said array and providedwith a plurality of individually movable tensioning members respectivelyaligned and engageable with said strands; first means for shifting saidsupport relative to said array for preliminarily tensioning saidstrands; and second means for shifting said members relative to saidsupport for final tensioning of the respective strands.

2. The improvement defined in claim 1 wherein said array liessubstantially in a horizontal plane and said first means includes apistonand-cylinder arrngement for raising and lowering said support.

3. The improvement defined in claim 2 wherein said device furthercomprises a traverse extending athwart said array on a side thereofopposite that along which said support extends, said traverse beingprovided with respective idler pulleys forming tensioning loops with therespective members of said support.

4. The improvement defined in claim 3 wherein said tensioning membersare upright blades carrying tensioning pulleys lying substantially incommon vertical planes with the respective idler pulleys and strand.

5. The improvement defined in claim 2 wherein said support is a cylinderblock and said second means includes a multiplicity of cylinder boresformed in said block in line with the respective strands, said membersincluding pistons respectively slidable in said bores and havingtensioning pulleys engageable with the respective strands.

6. The improvement defined in claim 5 wherein said cylinder block isprovided with channels for delivering hydraulic fluid to said bores inparallel.

7. The improvement defined in claim 6 wherein each of said pistons isprovided with a blade-shaped extension carrying the respectivetensioning pulley.

8. The improvement defined in claim 6 wherein said channels and saidbores are formed unitarily in said cylinder block.

9. The improvement defined in claim 2 wherein said second means includesfurther piston-and-cylinder arrangements carried by said support andindividual to said strand, said support being provided with channels forcommunicating a fluid medium to said further pistonand-cylinderarrangements.

10. The improvement defined in claim 2 wherein said second means is atensioning cable common to said tensioning members for transmitting atension force thereto in parallel.

References Cited UNITED STATES PATENTS 2,062,008 11/1936 Lewis et al.24258 3,072,360 1/1963 Cruz 242154 3,273,861 9/1966 Schuff 254 X3,276,938 10/1966 Malewski l56494 3,345,229 10/1967 Harpfer l56494 XROBERT F. STAHL, Primary Examiner US. Cl. X.R.

